Title of the document
Embedded System
What is an embedded system?
An embedded system is a combination of computer hardware and software designed for a specific function. Embedded systems may also function within a larger system. The systems can be programmable or have a fixed functionality.
What are the types of embedded system?
Ans. They are of 4 types
1. General computing
2. Control System
3. Digital Signal Processing
4. Communication and network
What is digital signal controller ?
Ans. DSC is 16 bit RISC machine that combines control advantages of micro-controller and digital signal processing to produce tightly coupled single chip-single instruction stream solution for embedded system design.
What are the components of embedded system?
Ans. Microcontroller, microprocessor, DSC, DSP, busses, system clock, Read only Memory(ROM), RAM, Real time clock these are the components of embedded system.
Why we use embedded systems?
Ans. Embedded systems avoid lots of electronic components and they have rich built in functionality. They reduces the cost and maintenance cost and the probability of failure of embedded system is less so embedded system are in very much use now a days.
What are the languages used in embedded system?
Ans. Assembly language and C are basically used for embedded system. Java and ADA are also preferred.
What is the significance of watchdog timer in ES?
Ans. It is a timing device which is set to predefined time interval and some task is to be performed at that time. It is used to reset original state when an inappropriate event take place. It is usually operated by counter device.
Mention what are the essential components of embedded system?
Essential components of embedded system includes
Hardware
Processor
Memory
Timers
I/O circuits
System application specific circuits
Software
It ensures the availability of System Memory
It checks the Processor Speed availability
The need to limit power lost when running the system continuously
Real Time Operating System
It runs a process as per scheduling and do the switching from one process to another
Mention how I/O devices are classified for embedded system?
The I/O devices of embedded system are classified into two categories
Serial
Parallel
Explain what are real-time embedded systems?
Real-time embedded systems are computer systems that monitor, respond or control an external environment. This environment is connected to the computer system through actuators, sensors, and other input-output interfaces.
Explain what is microcontroller?
The microcontroller is a self-contained system with peripherals, memory and a processor that can be used as embedded system.
Mention what is the difference between microprocessor and microcontroller?
Microprocessor is managers of the resources (I/O, memory) which lie outside of its architecture
Microcontroller have I/O, memory, etc. built into it and specifically designed for control
What does DMA address will deal with?
DMA address deals with physical addresses. It is a device which directly drives the data and address bus during data transfer. So, it is purely physical address.
Explain what is interrupt latency? How can you reduce it?
Interrupt latency is a time taken to return from the interrupt service routine post handling a specific interrupt. By writing minor ISR routines, interrupt latency can be reduced.
List out various uses of timers in embedded system?
Timers in embedded system are used in multiple ways
Real Time Clock (RTC) for the system
Initiating an event after a preset time delay
Initiating an even after a comparison of preset times
Capturing the count value in timer on an event
Between two events finding the time interval
Time slicing for various tasks
Time division multiplexing
Scheduling of various tasks in RTOS
Explain what is a Watchdog Timer?
A watchdog timer is an electronic device or electronic card that execute specific operation after certain time period if something goes wrong with an electronic system.
Explain what is the need for an infinite loop in embedded systems?
Embedded systems require infinite loops for repeatedly processing or monitoring the state of the program. For instance, the case of a program state continuously being verified for any exceptional errors that might just happen during run-time such as memory outage or divide by zero, etc.
What is ISR?
An ISR refers to the Interrupt Service Routines. These are procedures stored at specific memory addresses which are called when a certain type of interrupt occurs. The Cortex-M processors family has the NVIC that manages the execution of the interrupt.
What is a nested interrupt?
In a nested interrupt system, an interrupt is allowed to any time and anywhere even an ISR is being executed. But, only the highest priority ISR will be executed immediately. The second highest priority ISR will be executed after the highest one is completed.
The rules of a nested interrupt system are:
All interrupts must be prioritized.
After initialization, any interrupts are allowed to occur anytime and anywhere.
If a low-priority ISR is interrupted by a high-priority interrupt, the high-priority ISR is executed.
If a high-priority ISR is interrupted by a low-priority interrupt, the high-priority ISR continues executing.
The same priority ISRs must be executed by time order.
What is the boot-loader?
In general, a bootloader is a code that executes at the instant the CPU comes out of reset until it passes off control of the system to the OS. It performs basic initialization of the CPU and sometimes some other peripheral devices, such as disk subsystems, sometimes network controllers, perhaps timers, DMA controller, video controller, UART(s), etc.
What is RTOS?
RTOS stands for Real-Time Operating System. It specially designed to run the application with very precise timing and a high degree of reliability. An RTOS system must have response time predictability and it must be deterministic.
What is the kernel?
The kernel is a computer program that is the core of a computer’s operating system, with complete control over everything in the system. On most systems, it is one of the first programs loaded on start-up (after the bootloader). It handles the rest of the start-up as well as input/output requests from software, translating them into data-processing instructions for the central processing unit. It handles memory and peripherals like keyboards, monitors, printers, and speakers.
What are the differences between process and thread?
Threads differ from traditional multitasking operating-system processes in several ways:
The processes are typically independent, while threads exist as subsets of a process.
The processes carry considerably more state information than threads, whereas multiple threads within a process share process state as well as memory and other resources.
The processes have separate address spaces, whereas threads share their address space.
The processes interact only through system-provided inter-process communication mechanisms.
Context switching between threads in the same process typically occurs faster than context switching between processes.
Can MCU run code directly from flash?
Yes, Most of the MCU executes code directly from the flash.
List various timers in embedded systems?
Every MCU has a different list of timers. Here I am mentioning a few types of timers. If you know another one then please write a comment in the comment box I will add in this list.
Watchdog Timer (WDT)
General Purpose of Timer
Interval Timer (Programmable timer)
Cystic Timer
Real-Time Clock (RTC)
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